We call it re-purposing or customizing when we take something and change it to a different look or function. The following pictures, for instance, show how we changed four chairs over from casters to solid wooden leg tips, also called bun feet.
Top left is the original chair with casters, top right is the chair with the new bun feet glued on. First, we had to cut the leg above the brass trim (top left). Then after finding a bun foot (made by others) with wood grain (maple) that matched the original as well as possible and was in a shape that pleased the client, we cut the top inch off of the new foot, drilled holes in both chair leg and top of the new feet, colored and lacquered the feet to match the legs, then glued the feet and legs together with a metal dowel added for extra strength. NOT as easy as it looks.
The new feet had to be angled to match the existing leg and leveled to sit square on the floor, where the weight would be centered. Notice the bottom left picture, where the back legs are curved and angled oddly (see, the back left is not parallel to the front right leg - normal for this type of chair). It was difficult to match the angles of all four and clamp in a straight line, but with consummate skill (of course!) we managed to align all four feet on all four chairs. You have to really want this done though because it was about $130.00 or so per chair, if I remember right.